We focus on the example of the gap genes that are crucial in the early events of embryonic development in fruit flies [1]}, [2]}. These four genes form a network with inputs from primary maternal morphogen molecules, and outputs in the striped patterns of pair-rule gene expression. These stripes are positioned with an accuracy of \(\pm 1\%\)  along the long (anterior–posterior) axis of the embryo, and this is the accuracy of subsequent developmental events such as the formation of the cephalic furrow [3]}, [4]}. The local concentrations of the gap gene proteins provide just enough information to support this level of precision [3]}, and the algorithm that achieves optimal readout of this positional information predicts, quantitatively, the distortions of the pair-rule stripes in mutant flies where individual maternal inputs are deleted [6]}.
